Mold for heat curing thermosetting resins



Dec. 25, 1951 BR K 2,579,898

MOLD FOR HEAT CURING THERMOSETTING RESINS Filed May 3, 1949 MILTONBRUC/(ER,

INVENTOR. HUEBNERBEEHLERWORREL,

HERZ/G d CALDWELL,

ATTORNEYS.

Patented Dec. 25, 1951 i MOLD FORHEAT-CURING THERMOSET-TING .RESINS'MiltolfBrucker', Los Ang'eles',- Calif. ApplicationiMay 3', .1949,Serial No.391,054

6. Claims.

This invention relates to heat exchangers. More particularly, specificapplication. of the invention has been made for molds-for fusible orthermo-setting materials such as plastics and is likewise suitableforcertain metals, commonly molded.

It is intended by the instant invention to eliminate the old-fashionedmethod of heating molds in open ovens prior to the molding operation, orin the course thereof, and also ,to eliminate the complicated cast moldshaving fluid passages formed in the bodies thereof. Prior art molds andheat exchangers, particularly suited to molding operations, have eitherbeen massive and cumbersome requiring relatively elaborate fabricating:techniques, or, on the other hand, required transportation, regardlessof their size, from a station at which initial operations were performedto an oven in which thermosetting casting materials were cured. Chillingof prior art molds generally requires removal from the oven forsubjection to a refrigerantcold Water bath, etc.

Economy and facility of production of molds incorporating heat-exchangeconstruction are of importance, butof: hardly lesssig-nificance is the.efiiciency of the heat exchanger itself,its adaptability to variantenvironments or forms, and its convenience in use. In each and all ofthese respects it is intended .by the instant invention to improve overthe prior art means and methods of making and-using heat exchangers ingeneral and heat exchangers forthe-molding art in particular.

It is therefore among the objects of this invention, broadly, to providea newand improved heat-exchanger construction.

More specifically, it is an object of the invention to provide a new andimproved construction adapted for the efficient and effectivemanufacture and use of molds designed for the production of articles ofmanufacture wherein a heating phase, or a cooling phase, 'or both areemployed.

Other general objects of the invention are: The provision of a new andimproved heatexchanging apparatus for a prefabricated mold of anydesired configuratiomthe resultant construction:

(a) occupying a minimum ofspace,

(b) contributing a relatively insignificant weight factor,

() being facile of use,

(d) being adaptable to mass production methods,

(e) Saving time in the productiveprocess both during utilization of theheat exchanger and during application of the same as to a moldor thelike for use, and

(I) having unusual versatility in use-and in application.

Other more specific objects of the: invention also include withoutlimitation, provision of:

(a) a newand improved refrigeratingand/or heating conduit connection toand for heating and/or refrigerating a vessel, a space-heating-br arefrigerating, panel,

(b) improved means for bonding a conduit for the desired purposedescribed to a member whose temperature is to becontrolled,

(0) new and improved means for temporarily positioning a conduit meanspreliminary to fixing the-same in place in the desired manner and forthe desired purpose intended, and

(d) a new and improved Versatile means for producing a complete thermaldispersion of optimum efficacy between a refrigerating or heatingelement, whether electrical, fluid, orchemical, and a vessel, mold, orpanel, orthe like, the temperature of which is .to be governed.

It is, moreover, among the objects of the invention to provideimprovements over prior art devices heretofore contemplated forgenerally similar purposes includingrapidly and efficiently elevatingthe temperature of a member, maintaining said member at such desiredtemperature with uniformity of effectiveness, rapidly changing suchtemperature throughthe agency of the heat exchanger and without thenecessity of transporting the subject member from .one stationto anotherorbringing'. it underzthe influence of external atmosphericor similarenvironmental influences, and all interfering to a minimum possibleextent with thetother uses and-procedures surrounding the intended. useof the subject equipmentand material, as 'the'application of moldingpressures thereto.

With these and other objects in :view,the invention consists in theconstruction, arrangement and'combination of the various parts of thedevice whereby the objects contemplated are attained, as hereinafterset'forth, pointed out in the appended claims, and illustrated in theaccompanying drawings.

In the drawings:

Figure l is an elevational view, parts being cut away, of a conicalshaped mold embodying-this invention.

Figure 2 is a perspective view of a slightly concave mold memberembodying this invention.

Figure 3 is a plan view of aflat, heat-exchange panel or moldembodyingthis invention.

Figure 4 is a detailed sectional view takenas on a line 4-4of Figure 3.

Figure 5 is a similar detailed view taken as on a line 55 of Figure 3.

Figure 6 is a view like Figures 4 "and 5 of another furthermodifiedheat-exchanger construction embodying this invention employing anelectrical heating element.

Referring more particularly to the drawings, a

may be of a single continuous length or of several runs interconnectedby headers in parallel or reticulate fashion.

In Figure 1,-the conduit takes the shape of a helical coil of copper orother tubing l5 and is spirally wound about the wall If of the moldmember, preferably in continuous contiguity with the external wallsurface [2.

A coil inlet for a fiuid refrigerant or heating agent maycomprise thepipe I! fitted as with a threaded union 8. The inlet pipe H is connectedas to a valve l9 having a handle by means of which the inlet pipe ll mayselectively receive, as from a pipe 2i connected with a source of steamor the like agent for heating the coil E5, or to a pipe 22 connected toa source of cold water or refrigerant for chilling said coil i5.

An outlet pipe 23 may be similarly secured as by another union 24 to anopposite end of the coil E5 to permit the circulation of the steam orwater from the coil [5 to a pump 25 for re-heating, cooling,recirculation, or disposal. Any fluid remaining in the coil can beevacuated by the pump.

Between adjacent loops 28 of the coil 15 a coating of metal 36 issprayed and deposited upon and in coherent relationship to the externalsurface 12 of the mold wall and in a manner to form fillets 3! in thecorners between the adjoining surfaces of the wall [4 and the tubing E5.The sprayed coat may comprise zinc, aluminum, copper or any othersprayable metal of good heat conductivity. The metal spray is producedby blowing the fused metal from an electric or acetylene torch inaccordance with known metal spraying methods.

The coating 3t thus formed is preferably, though not essentially, alsocontinuous over the entire external surface of the coil and of the moldincluding the upper end 33of the mold as well as the outermost surfaceportions 34 of the tubing. Thereby in effect, a blanket of conductivematerial may be distributed over the entire exterior mold surface inintimate relationship with the tubing or conduit and also with theexternal mold surface l2.

The fillets (ii are built up adjacent the areas ofproximity of the coilsand the molds to provide a direct, intimate and effective bond foroptimum thermal dispersion between the tubing and the mold. It is thefillet thickness, as shown hereinafter, that is critical.

In theothers, as well as in the instant embodiment, it has been foundthat the mold and tubing may be exposed to the room temperature andatmosphere during the heating and/or cooling process. If desired,however, a layer of insulative ma.- terial may-be applied to theexterior surface of the'mold and tubing for retaining any heatotherwise, lost through convection and radiation.

Referring now to the form of Figure 2, a mold member 5ii} may comprise.a concave or other suitably shaped interior surface 5! of a cast metalwall 52 preferably of uniform thickness throughout and havingreinforcing ribs 53 transversely and 55 longitudinally thereof.Optionally, the wall 52 and'the reinforcingribs 53 and 54 are castintegrally. In any event, they should be formed with holes 56 in orderthat a metal conduit 51, preferably of a flexible variety, formed withor without radiating fins, may be more readily wound in a sinuous routeover the exterior surface 58 of the mold wall 52. After passing theconduit 51 through the several openings 56 in a manner to mosteffectively comprehend the exterior surface 58 of the mold, any suitablestraps 60 may be provided for holding the conduit against the moldsurface 58.

Thereupon, or at a prior stage if desired, the external surface 58 andthe conduit 51 are thoroughly sand blasted, or otherwise etched,roughened, and cleaned toinsure the most coherent contact of the sprayedmetal with the mold and tubing surfaces.

The metal coating bein then applied primarily in the fillet region andalso if desired over the surface of the conduits and the outside surfaceof the mold by standard metal spray process, as heretofore stated, fillsup the corners between the conduits and the adjoining surface of themold and may cover as well the exposed surface of the conduits and theentire external surface of the mold. It is important to note that thefillet forms a direct heat conductive bond between the coil and themold. The coating in other areas, as over the tubing surfaces andbetween adjacent coils, may be omitted with somewhat of a loss in totalconductive efficiency, or a narrow ribbon normally made by the spraymay, alone, be left. The mold itself is conductive in either event.

The ends 62 and 63 of the conduits may then be connected to a source ofsteam or other heating element, or cold water or other refrigeratingelement, or both, as heretofore stated.

The straps may secured in any desired fashion to the wall 52, but inorder to avoid distortion of the tubing or the inner mold surface 51 bywelding or similar processes supplying any undue amount of heat,securements such as screws 5G may be inserted in a well-known mannerinto holes drilled into the outer side 58 of the mold wall 52 If themold can be laid flat so that no tendency will exist for the conduit tomove out of a preset position, the straps or the like 68 may bedispensed with and the metal coating 65 directly applied by spraying, asaforesaid, over the outer surface of the mold and, primarily, in theform of fillets between the conduit and the mold. The sprayed metal willthen alone hold the tubing in place.

As illustrated in Figures 3, 4, and 5, any suitable heat exchanger, suchas a panel I60, Whether curved, right-lined, square, round, or othergeometric shape, may beprovided with zigzagging coils lfil.Preliminarily, these may be secured in place as by straps til, held inplace as by screws 64.

The surface of the tubing comprising the coils lill, as well as theadjacent surface of the panel IE0, is again sand-blasted, or otherwisescoured, roughened, and cleaned. A metal we is then sprayed, asaforesaid, forming a coating over the panel I08 on one or both sidesthereof including thesurfaces of the coils It i. Fillets I01 maylikewise be formed between the conduit comprising the-coilsand--the'adjacent surface of the heat exchanger panel 1 I 60, 1 as -hei-etofore stated.

"The connectionof the screws 64 to the panel H30, as Icy-means of holesI09 drilled partly through the same, may be seen most clearly in Figure4 where the exterior or upper surface of the panel is designated by thenumeral Ill] and the inner-or bottom'surface is designated by thenumeral III. By reference to Figures 3 and 4, it will be apparent thatthe metal covering I05 preferably forms a continuous coating over thecoils IiiI as at thetop surface H3 thereof and also in the area -I I4between adjacent coil loops H6.

In this, as in the other embodiments, the fillets I01 may; but need not;be as deep as illustrated and the surface N8 of said fillets may have astraight or curved profile in cross-sectional view. If desired, thefillets may be relatively shallow, the coating thicknessin the deepestportion of the fillets being only equal to or slightly greater thanthatat the top I I3 or" the'conduit or in the area H4 between adjacentloops'thereof, but the rate of conductivity will be less than with athicker fillet, other things being equal.

In Figure 6 another further modified form of construction embodying thisinvention comprises a panel, wall, or other member I50, corresponding toany of the previousembodiments heretofore described, including a'filletI5! of sprayed metal coherent to one surface I52. A conduit I 53similarly disposed over the surface I52 to those heretofore described,contains a refractory material i5 1 separating the conduit I53 from anelectrical heating element [55. By such construction, the member I50 maybe heated electrically in lieu of the fluid-heating element or agentcontemplated for the previously described embodiments of the invention.

It will be apparent that in lieu of the fluid or electrical conduit I55,chemically produced heat, as by exothermic reaction, or cold, as byendothermic reaction, may perform a similar heating or refrigeratingfunction.

It has been found that by the utilization of the instant invention, themetal spray is adequate to retain the conduit in position on the outersurface of the mold, or the like, and, What is even moreimportant, thecoating of sprayed metal effects a complete dispersion of heat or coldpassing through the conduit or originating therein.

Tests have been made to determine the relative advantages of variousforms of metal utilized for the spray or otherwise deposited covering,as well as to compare the relative eificiency of the instant inventionwith prior molds and practices. Some of these follow:

Example No. 1

A mold utilizing a steam coil was used to make a part comprising a fiberglass matrix impregnated with Selectron, an unsaturated polyester resin.One-half inch nominal size copper tubing in a continuous helical-typecoil 21 feet in length was secured by straps and screws to an aluminummold of one-half inch wall thickness. The total weight of the mold was250 pounds. The same, being of only one female half, was formed in thegeneral shape of a hemisphere approximately 12 inches in radius andcomprising only a female part having an approximate length and width of32 inches, respectively, and a total surface area of approximatelysquare feet. Molding pressure was applied by a flexible vacuum bag.

The coils were approximately 4 inches apart between centers on only theconvexside of the mold where they were subjected to a thorough sandblasting and thereafter spray coated with zinc by means of a metal spraygun to a thickness between the coils of approximately one-sixteenth ofan inch and with a fillet thickness from side to side of the tubing ofapproximately onefourth of an inch.

When subjected to sixty pounds ofsteam pres-- sure within the coil,maintaining atemperature equivalent to approximately 260 degreesFahrenheit therein, the mold was'brought'up to acuring temperature ofapproximately 200'to 210 degrees Fahrenheit in approximately nineminutes, and the resin was completely cured in a total time, beginnin atroom temperature, of approximately 35 minutes.

The same hemisphere subjected to the same general environment but curedin an oven required approximately 25 minutes to come upto the curingtemperature at an oven temperature of approximately 266 degreesFahrenheit, and approximately 38 minutes at an oven temperature of 225degrees Fahrenheit. The total curing time in the oven at the formertemperature, 2-36 degrees Fahrenheit, was approximately one hour.

Example N0. 2

A mold utilizing a steam coil was used to make a part comprising a fiberglass matrix impregnated with Selectron. Flexible bronze tubing in acontinuous coil 30 feet in length was secured by straps and screws toanaluminum mold. The coil was of one-half inch nominal tubing size. Themold wall thickness was three-fourths of an inch. Total weight of themold was 200 pounds. The mold was formed in the shape of a quartershell16 inches deep having an approximate length and width of 20 and 14inches, respectively, and a. total surface area of approximately sevensquare feet.

The coils were arranged four inches apart and secured to the externalsurfaces of both the male and female halves of the mold where they weresubjected to a thorough sand blasting and thereafter coated withaluminum by means of a metal spray gun to a thickness between the coilsof approximately one-sixteenth of an inch and. with a fillet thicknessof approximately one-fourth of an inch.

When subjected to sixty pounds of. steam pressure within the coil, themold was again brought up to a curing temperature of approximately 200to 210 degrees Fahrenheit in approximately 10 minutes and the resin wasagain cured in a total time, beginning at room temperature, ofapproximately 25 minutes.

The same molded product'required 90 minutes curing time in an oven at anoven temperature of 260 degrees Fahrenheit.

Example No. 3

A mold utilizing a steam coil was used to make a part comprising a fiberglass matrix impregnated with Selectron. Bronze flexible tubing in acontinuous coil 74 feet in length was secured by straps and screws to analuminum mold. The coil was of one-half inch nominal tubing size. Themold wall thickness was three-fourths of an inch. Total weight of themold was 440 pounds. The mold was formed in the shape of a half teardropapproximately 18 inches deep, and having an approximate length of inchesand width of 28 inches, respectively, and atotal surface area ofapproximately 21 square feet.

'The coils were arranged four inches apart and secured to the externalsurface of both the male and female halves of the mold where they weresubjected to a thorough sand blasting and thereafter coated with zinc bymeans of a metal spray gun to a thickness between the coils ofapproximately one-sixteenth of an inch and with a fillet thickness ofthree-eighths of an inch.

When subjected to sixty pounds of steam pressure within the coil, themold was brought up to a curing temperature of approximately 200 degreesFahrenheit in approximately 10 minutes and the resin was cured in atotal time, beginning at room temperature, of approximately 40 minutes.

The total curing time in an oven at the 260 Fahrenheit temperature wasapproximately 90 minutes.

' Example No. 4

A mold utilizing a steam coil was used to make a part comprisingParaplex, an unsaturated polyester resin. Copper tubing in a continuouscoll 110 feet in length was secured by Welded straps to a nickel mold.The coil was of threeeighths inch nominal tubing size. The mold wallthickness was five-sixteenths of an inch. Total weight of the mold was300 pounds. The mold was of only one piece and was formed in the shapeof a parabola 28 inches deep having an approximate length of 49 inchesand width of 42 inches, respectively, and a total surface area ofapproximately 38 square feet. Molding pressure was applied by means of aflexible diaphragm pulled into place by a vacuum.

The coils were arranged two inches apart and secured to only the convexexternal surface of the female mold Where they were subjected to athorough sand blasting and thereafter coated with zinc by means of ametal spray gun to a thickness between the coils of approximatelyonesixteenth of an inch and with a fillet thickness of approximatelyone-fourth to three-sixteenths of an inch. When subjected to sixtypounds of steam pressure within the coil, the mold was brought up to acuring temperature of approximately 200 to 210 degrees Fahrenheit inapproximately 10 minutes and the resin was cured in a total time,beginning at room temperature, of 30 minutes.

The total curing time in an oven at an oven temperature of 260Fahrenheit was approximately 130 minutes.

Example N0.

A mold utilizing a steam coil was used to make a part comprising a fiberglass matrix impregnated with Selectron. Bronze flexible tubing in acontinuous coil 90 feet in length was secured by straps and screws to analuminum mold. The coil was of one-half inch nominal tubing size. Themold wall thickness was one-half inch. Total weight of the mold was 1480pounds. The mold, of only one piece, was formed in the shape of anairplane fin 34 inches deep having an approximate length of '78 inchesand width of 16 inches, respectively, and a total surface area ofapproximately 32 square feet. The coils were arranged four inches aparton the outer side of the mold and secured thereto whereupon they weresubjected to a thorough sand blasting and thereafter coated with zinc bymeans of a metal spray gun to a thickness between the coils ofapproximately one-sixteenth of an inch and with a fillet whose thicknesswas approximately one-fourth of an inch. When subjected to sixty poundsof steam pressure within the coil, the mold was brought up to a curingtemperature of approximately 200 degrees Fahrenheit in approximately 10minutes and the resin was completely cured in a total time, beginning atroom temperature, of 70 minutes.

The total curing time in an oven at the 260 Fahrenheit temperature wasapproximately minutes.

In each of the above examples the packed molds required 25 minutes at anoven temperature of approximately 260 Fahrenheit and 30 minutes at anoven temperature of 225 Fahrenheit to come up to a desired moldingtemperature of 200-210 Fahrenheit.

The figures given, though based on direct observation, are approximate.

Thus, it has been experimentally determined that steam-carrying coilssecured by sprayed metal to the exterior surface of a mold, afterthoroughly sand blasting the mold and the conduit, are in generalcontrolled by the thickness of the fillet and character of the metalsemployed in the mold, the coils, and the deposited metal uniting thetwo. speedier heat conductivity is also a function of decreasing moldthickness, increasing tubing size and more proximate coil spacing. Whencoils otherwise similar in size and material are spaced relativelyclosely apart over the surface of the mold, curing temperatures areachieved more rapidly. Spacially uniform mold temperatures are obtainedonce the mold has been heated to a desired temperature. The aboveexamples are illustrative ofa satisfactory group of working conditionssuccessfully used in fabrication of air frame parts for airplanes.Polymerization was uniform and entirely satisfactory.

Copper has been found best for spraying purposes as a coating from thestandpoint of heat conductivity, corresponding in this respect to thehigh heat conductivity of this substance. However, zinc was found tospray approximately three times as fast as copper and has therefore beenpreferred. Aluminum has also been used to advantage. This designation ofparticular metals is intended, however, merely as illustrative.

The thickness of the coating built up on the coil and adjacent surfacesdoes not appear critical. With any given materials, however, bestresults are obtained when the fillet connection between the tubing andthe mold is thickest. Excellent results are accomplished when the filletthickness from side to side of the tubing is equal to at least one-halfof the diameter of the tubin in accordance with the following table:

Tubing Fillet Fillet Size Width Thickness Inches Inches Inches M it i itt% tie if %1 ii it 1-1 it it containing a catalyst such as benzoylperoxide; Marco, an unsaturated polyester resin contain ing a catalystsuch as benzoyl peroxide; and Thalid, a polyester resin containing acatalyst such as benzoyl peroxide.

Another decided advantage of the instant invention is that maybe used-inplace upon the Workshop floor and need not be transported from place toplace. Thus, connections tothe coils forheating or chilling the samecircumvent otherwise required movement of the mold from station tostation during various stages of packing the mold, compressing the same,if required, heating and chilling, etc.

This invention features the provision of. new and improved structure andmeans for making a thermal bond and for conduction of heat or cold froma circulating coil or its equivalent to the exterior surface and henceto the body of a mold or other subject member. The means employedcontemplate first a thorough cleansing and roughening of the subjectsurfaces followed by metal spraying to form a relatively wide area ofcontact between a heating coil or the like and a subject surface,particularly at and immediately adjacent the line of contact betweensuch coil and such surface.

Other means of depositing a metal coating have been contemplatedincluding electro-plating and while such other procedures are possible,they are generally too slow to be commercially practical, while directpainting, as with a brush, of metallic binding agents, achieves a lesssatisfactory thermal dispersion and an inferior metal-to-rnetal contactthan herein contemplated.

Metal spraying is herein referred to. It is not required, however, thatmetal coils or metal molds or the like be used. Any substance capable ofcarrying a heating or refrigerating agent can be used, such as plasticor even rubber, provided they are capable of union with the other member(coil or panel) by a metal spray process as herein referred to.

As noted, the invention may be used for heat exchangers in general,including, without limitation, vessels for cooking, around which coilsmay be wound, coil construction for refrigerators or freezers, for spaceheaters, radiating panels, and the like.

Although the invention has been herein shown and described in what isconc ived to be the most practical and preferred method and embodiment,i is recognized that departures may be made therefrom within the scopeof the invention, which is not to be limited to the details disclosedherein but is to be accorded the full scope of the claims so as toembrace any and all equivalent structures and methods.

The invention having been herein described, what I claim as new anddesire to secure by Leters Patent is:

l. A mold for heat curing thermosetting resins and the like, said moldhaving an inner surface of a configuration conforming to that of thearticle to be molded and an outer surface of generally similarconfiguration to that of said inner surface, metal tubing engaged inintimate line contact with said outer surface, said tubing being bent ina suitable configuration to substantially uniformly overlie said outersurface with portions of the tubing substantially uniformly spaced apartand distributed over the area of said outer surface, means securing saidtubing to said outer surface at intervals along the length thereof tohold the same in contact with said outersurface, heat conducting metalin the interspaces between said tubing and said outer surface along therespective sides of the line of contact of said tubing with said outersurface, said heat conducting metal thus forming fillets fortransferring heat from said tubing to said mold, and a layer of heatconducting metal of substantially uniform thickness covering theportions of the tubing and said outer surface which is not engaged bysaid fillets.

2. A mold for heat curing thermosetting resins and the like, said moldcomprising a sheet of heat conducting material of substantially uniformthickness having an inner surface of a configuration conforming to thatof the article to be molded, relatively thin-walled metal tubing engagedin intimate line contact with the outer surface of said sheet, saidtubing being bent in a suitable configuration to substantially uniformlyoverlie said out-er surface with portions of the tubing substantiallyuniformly spaced apart and distributed over the area of said outersurface, means securing said tubing to said outer surface at spacedintervals along the length thereof to hold the same in firm line contactwith said outer surface, heat conducting metal in the inter-spacesbetween said tubing and said outer surface along the respective sides ofthe line of contact of said tubing with said outer surface, said heatconducting metal thus forming fillets for transferring heat from saidtubing to said mold, and a continuous layer of heat conducting metal ofsubstantially uniform thickness covering and fused t the otherwiseexposed portions of the tubing and said outer surface and fillets, saidlayer being of a thickness of the same order of magnitude as thethickness of said tubing wall.

3. A mold, as defined in claim 1, wherein the tubing has a diameter ofof an inch to inch and adjacent portions of the tubing are spaced apart'2 inches to 4 inches over the outer surface of the mold.

4. A mold, as defined in claim 1, wherein the tubing is to inch indiameter, and the width of the fillet between the tubing and the outersurface of the mold is of an inch to A; inch in width, and the thicknessof the layer of heat conducting metal covering the tubing and the outersurface of the mold is about 3 of an inch.

5. A mold, as defined in claim 1, in which the tubing is copper and theheat conducting metal forming the fillets and layer of covering materialis zinc.

6. A mold for heat curing thermosetting resins and the like, said moldhaving an inner surface of a configuration conforming to that of thearticle to be molded and an outer surface of generally similarconfiguration to that of said inner surface, metal tubing engaged inintimate line contact with said outer surface, said tubing being bent ina suitable configuration to substantially uniformly overlie said outersurface with portions of the tubing substantially uniformly spaced apartand distributed over the area of said outer surface, means securing saidtubing to said outer surface at spaced intervals along the lengththereof to hold the same in contact with said outer surface, heatconducting metal in the inter-spaces between said tubing and said outersurface along the respective sides of the line of contact of said tubingwith said outer surface, said heat conducting metal thus forming filletsfor transferring heat from said tubing to said mold, and a layer of heatconducting metal of substantially uniform thickness covering exposedsaid fillets.

I Number portions of the tubing and the outer surface of MILTON BRUCKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 1,027,831 Fox May 28, 1912 1,767,062Glidden et a1 June 24, 1930 1,800,150 Musgrave et al Apr. 7, 19311,841,762 Samesreuther Jan. 19, 1932 1,847,573 Rupp Mar. 1, 19322,006,299 Kaestner June 25, 1935 Engstrom June 29, 1937 Number 2,145,4602,172,604 2,173,588 2,182,400 2,271,437 2,280,865 2,317,597 2,330,371 102,359,013 2,476,994

Number 15 476,171 693,125

1. A MOLD FOR HEAT CURING THERMOSETTING RESINS AND THE LIKE, SAID MOLDHAVING AN INNER SURFACE OF A CONFIGURATION CONFORMING TO THAT OF THEARTICLE TO BE MOLDED AND AN OUTER SURFACE OF GENERALLY SIMILARCONFIGURATION TO THAT OF SAID INNER SURFACE, METAL TUBING ENGAGED ININTIMATE LINE CONTACT WITH SAID OUTER SURFACE, SAID TUBING BEING BENT INA SUITABLE CONFIGURATION TO SUBSTANTIALLY UNIFORMLY OVERLIE SAID OUTERSURFACE WITH PORTIONS OF THE TUBING SUBSTANTIALLY UNIFORMLY SPACED APARTAND DISTRIBUTED OVER THE ARE OF SAID OUTER SURFACE, MEANS SECURING SAIDTUBING TO SAID OUTER SURFACE AT SPACED INTERVALS ALONG THE LENGTHTHEREOF TO HOLD THE SAME IN CONTACT WITH SAID OUTER SURFACE, HEATCONDUCTING METAL IN THE INTERSPACES BETWEEN SAID TUBING AND SAID OUTERSURFACE ALONG THE RESPECTIVE SIDES OF THE LINE OF CONTACT OF SAID TUBINGWITH SAID OUTER SURFACE, SAID HEAT CONDUCTING METAL THUS FORMING FILLETSFOR TRANSFERRING HEAT FROM SAID TUBING TO SAID MOLD, AND A LAYER OF HEATCONDUCTING METAL OF SUBSTANTIALLY UNIFORM THICKNESS COVERING THEPRODUCTS OF THE TUBING AND SAID OUTER SURFACE WHICH IS NOT ENGAGED BYSAID FILLETS.